Thermal protectors that open/close a contact by inverting and driving a bimetal with Joule heat produced by an applied current are known as conventional techniques.
Most of these thermal protectors incorporate a resistor, such as a film resistor (for example, see Patent Document 1), a metal wire resistor (for example, see Patent Document 2) or the like, for producing Joule heat as an additional component in order to take measures in response to not only an increase of an ambient temperature but an overcurrent.